With Google Maps API V3, determine if a marker is inside a KML Layer boundary

Question

Is there a way to determine if a marker has entered an area covered by a KmlLayer? My .kml is mostly made up of a with a bunch of coordinates that

Answer 1

I had a request to provide more detail on how I implemented this. You can see an example here: http://www.usinternet.com/fiber-info/map.php

I have a couple markers on the map, and I want to test if they are inside or outside a boundary. I set them up like this:

        var userLocation = new google.maps.LatLng(44.928633,-93.298919);    //Lyndale Park

        var wendysLocation = new google.maps.LatLng(44.948056,-93.282222);  //Wendy's on Lake St

        var userMarker = new google.maps.Marker({
            position: userLocation,
            map: map,
            title:"Your Location",
            draggable: true
        });

        var wendysMarker = new google.maps.Marker({
            position: wendysLocation,
            map: map,
            title:"Wendy's on Lake St",
            draggable: true
        });

To create the polygon you need something to read the KML file and build a set of coordinates, which can then be added to the polygon's paths: property. Unfortunately it doesn't seem like you can go from KML to Polygon just using the Google Maps API, but somebody correct me if I'm wrong!

var sector3PillburyPleasant = new google.maps.KmlLayer('http://usinternet.com/fiber-info/kml/Sector3Pillbury-Pleasant.kml', kmlOptions);
            sector3PillburyPleasant.setMap(map);

            var coordsSector3PillburyPleasant = [
                new google.maps.LatLng(44.91615269014508, -93.28382953316716),
                new google.maps.LatLng(44.91619137463104, -93.28120338511586), 
                new google.maps.LatLng(44.93046751403393, -93.28114057929436),
                new google.maps.LatLng(44.93046991974436, -93.28055243604703),
                new google.maps.LatLng(44.94815274527994, -93.28053962401711),
                new google.maps.LatLng(44.94815856171297, -93.28364017122617),
            ];

            var polySector3PillburyPleasant = new google.maps.Polygon({
                paths: coordsSector3PillburyPleasant,
                strokeColor: "#FFFFFF",
                strokeOpacity: 0.0,
                fillColor: "#FFFFFF",
                fillOpacity: 0.0
            });

I parsed the polygon's path down from the KML, the coordinates that make up the path were nested like this: (the last coordinate pair isn't needed if you are closing the path.)

    
        
            1
            
                
                    
                        -93.28382953316716,44.91615269014508,0 -93.28120338511586,44.91619137463104,0 -93.28114057929436,44.93046751403393,0 -93.28055243604703,44.93046991974436,0 -93.28053962401711,44.94815274527994,0 -93.28364017122617,44.94815856171297,0 -93.28382953316716,44.91615269014508,0 
                    
                
            
        
    

Then I test whether the marker's I've got are inside or outside of the polygon:

        var markerIn = google.maps.geometry.poly.containsLocation(wendysMarker.getPosition(), polySector3PillburyPleasant);

        var markerOut = google.maps.geometry.poly.containsLocation(userMarker.getPosition(), polySector3PillburyPleasant);

        console.log(markerIn);

        console.log(markerOut);

Then you've got yourself a true or false test if you are inside or outside the KML layer, though there was a bit of a detour to turn the KML layer into a Polygon.